Increasing vitamin D levels had no effect on calcium absorption in young women, researchers reported.

Action Points

Increasing vitamin D levels had no effect on calcium absorption in young women.

Point out that the study suggests that there is no need to recommend vitamin D for increasing calcium absorption in normal people.

Increasing vitamin D levels had no effect on calcium absorption in young women, researchers reported.

In an ancillary result from a randomized clinical trial, women who started out with vitamin D insufficiency were brought up to normal levels through supplements over a 1-year period, according to Christopher Gallagher, MD, of Creighton University Medical Center in Omaha, and colleagues.

But baseline serum levels of 25OHD and calcitriol (1,25(OH)2D) were not predictive.

Findings were similar for serum levels of 25OHD at 12 months, Gallagher and colleagues reported.

The study is the first randomized trial to look at the issue in younger women, the investigators concluded, and a study in older women, using similar doses, found much the same thing.

At higher vitamin D doses, however, there was a small increase in calcium absorption, they noted. Gallagher and colleagues also noted that analyses of adolescent girls and children have also found no increase in calcium absorption with higher levels of vitamin D.

They cautioned that the single isotope method of measuring calcium absorption is probably a less accurate technique than the double isotope approach, although results of the two types are highly correlated.

The study was supported by the Department of Defense. Gallagher reported receiving calcium tablets from Bayer Pharmaceuticals at no cost; other authors reported no conflicts of interest.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner